How to Make a Simple AC Reverse Polarity False Indicator

Thread Starter

paperring

Joined Feb 11, 2017
11
Hi.
I want to switch a 220V 18A AC motor with an SSR. To make this safely I want to make a simple AC reverse polarity indicator. When plug in the motor to wall socket, the hot line must be connected to fuse and SSR. Also at wall socket there is no ground. Can I use this circuit for this job https://goo.gl/6Ekcq0 Any idea?
 

MaxHeadRoom

Joined Jul 18, 2013
28,619
That is about a 5hp motor, how do you intend to control it with a SSR, i.e. Input circuit?
There is no 'Reverse polarity' on 1ph AC?
I assume you are not in N.A. if one side of 220v is N.
Also most places that would not conform to code if you cannot earth the frame of the motor.It is not safe.
Max.
 

Thread Starter

paperring

Joined Feb 11, 2017
11
I bought one of these 40A/250V SSR. As we know that at wall socket there are three line: hot, neutral and ground. I know it is not safe but in this case I have to. I just want to sure that plug in the motor correctly to wall socket that hot line connected to SSR and fuse.
 

crutschow

Joined Mar 14, 2008
34,284
I bought this 40A/250V SSR. As we know that at wall socket there are three line: hot, neutral and ground. In this case I have no ground. I just want to sure that plug in the motor correctly to wall socket that hot line connected to SSR and fuse.
There's no way to distinguish between hot and neutral without a ground connection.
 

MaxHeadRoom

Joined Jul 18, 2013
28,619
Yes but how are you controlling the 3v to 30v input? Why do you need to ensure the Hot line it switched? Normally you would have a polarized plug and socket.
If you are concerned about connecting properly the motor should be grounded in most municipalities.
Also the inrush of a 5hp motor is considerable, could be a problem when using a small SSR.
Max.
 

Thread Starter

paperring

Joined Feb 11, 2017
11
Yes but how are you controlling the 3v to 30v input? Why do you need to ensure the Hot line it switched? Normally you would have a polirized plug and socket.
If you are concerned about connecting properly the motor should be grounded in most municipalities.
Also the inrush of a 5hp motor is considerable, could be a problem when using a small SSR.
Max.
I will use 12VDC input from the same AC line with a DC converter and simple resistor-led-switch. I know motor must grounded properly but there is no ground line and I have to use that motor.
 
Last edited:

Thread Starter

paperring

Joined Feb 11, 2017
11
When it plug in, the input led will indicate that circuit is powered. I use an SSR because SSR's have no mechanical components and I thought that this way may more durable than mechanical switch on hot line.
 

MaxHeadRoom

Joined Jul 18, 2013
28,619
When it plug in, the input led will indicate that circuit is powered. I use an SSR because SSR's have no mechanical components and I thought that this way may more durable than mechanical switch on hot line.
Personally I would use a motor contactor for that size of motor.
These also have the option of over loads.
I assumed Europe somewhere for 220 L & N, you should be able to fit a polarized plug if worried about reverse connection.
Max.
 

Thread Starter

paperring

Joined Feb 11, 2017
11
Personally I would use a motor contactor for that size of motor.
These also have the option of over loads.
I assumed Europe somewhere for 220 L & N, you should be able to fit a polarized plug if worried about reverse connection.
Max.
Maybe you are right. Maybe I have to use a circuit breaker and a contactor. But, is there any way to achive this job with an SSR and no ground line?
 

MaxHeadRoom

Joined Jul 18, 2013
28,619
It will work without a earth ground but usually not considered safe, what is the normal regulations where you are using the motor?
Using the SSR is taking a risk, especially if it starts on load.
Max.
 

Thread Starter

paperring

Joined Feb 11, 2017
11
I will use this motor in a country house in Turkey. As circular saw bench to cut firewoods. The building has no grounding so kind of an unlicensed electric installation. I know this is unsafe but people in here use this kind of motors without having a problem. Why SSR's are unsafe? These relays widely preferred for high current switching.
 

profbuxton

Joined Feb 21, 2014
421
Why would you want to use a SSR? Just plug motor into outlet, switch on and go. Surely its that simple. Just be aware of motor starting current.
 

BR-549

Joined Sep 22, 2013
4,928
Install polarized plugs and receptacles....whether you use a ground wire or not. For the polarity.

Use at own risk.
 

MaxHeadRoom

Joined Jul 18, 2013
28,619
What kind of receptacle are you using for a 5hp motor, most installations, this would be too small for a regular outlet.
As to your original question, it won't make any difference in your case what line you place the SSR in.
Max.
 
Top